In addition to Game of Thrones star Bradley playing the first Doctor, just as he’d portrayed actor William Hartnell in a BBC movie about the series, the special will feature fellow HBO star and Doctor Who writer Mark Gatiss as World War One soldier “The Captain.” The trailer also revealed that Pearl Mackie will reprise her role as Bill, though it remains to be seen if she’ll stay on for any part of Whittaker’s tenure in 2018.

Our new Doctor will also begin Season 11 in spring 2018 under new showrunner Chris Chibnall, replacing the departed Steven Moffat. The panel also offered a retrospective of Capaldi’s work on the show.

We’ll have plenty more to see before Christmas as we gear up for Capaldi’s sendoff and Jodie Whittaker’s arrival, so stay tuned for the latest from Doctor Who.